Around the time Sonic and Knuckles was FINALLY released on virtual console my friend and I decided to tackle these. Of course we made a drinking game of it so we ended up failing miserably eventually but... It was fun.

Maybe it's because I played these two games more than any other (not just Sonic - I mean more than any other game EVER), but these Special Stages are still a walk in the park for me. I'd say, in terms of difficulty:
Sonic 2>Sonic 1>Sonic CD>Sonic 3 & Knuckles.
I played lots of Sonic CD too...

battlefront 2: galactic conquest mode; when that other ship threatened a space battle toi feared for both your fleet and up to an hour of yoir time. Although yes. this always was quite scary, nice idea, my good sir.